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shaka-packager/packager/hls/base/media_playlist.cc

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// Copyright 2016 Google Inc. All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file or at
// https://developers.google.com/open-source/licenses/bsd
#include "packager/hls/base/media_playlist.h"
#include <algorithm>
#include <cmath>
#include <memory>
#include "packager/base/logging.h"
#include "packager/base/strings/stringprintf.h"
#include "packager/media/base/language_utils.h"
#include "packager/media/file/file.h"
#include "packager/media/file/file_closer.h"
#include "packager/version/version.h"
namespace shaka {
namespace hls {
namespace {
uint32_t GetTimeScale(const MediaInfo& media_info) {
if (media_info.has_reference_time_scale())
return media_info.reference_time_scale();
if (media_info.has_video_info())
return media_info.video_info().time_scale();
if (media_info.has_audio_info())
return media_info.audio_info().time_scale();
return 0u;
}
std::string CreatePlaylistHeader(const std::string& init_segment_name,
uint32_t target_duration,
MediaPlaylist::MediaPlaylistType type,
int sequence_number,
int discontinuity_sequence_number) {
const std::string version = GetPackagerVersion();
std::string version_line;
if (!version.empty()) {
version_line =
base::StringPrintf("## Generated with %s version %s\n",
GetPackagerProjectUrl().c_str(), version.c_str());
}
// 6 is required for EXT-X-MAP without EXT-X-I-FRAMES-ONLY.
std::string header = base::StringPrintf(
"#EXTM3U\n"
"#EXT-X-VERSION:6\n"
"%s"
"#EXT-X-TARGETDURATION:%d\n",
version_line.c_str(), target_duration);
switch (type) {
case MediaPlaylist::MediaPlaylistType::kVod:
header += "#EXT-X-PLAYLIST-TYPE:VOD\n";
break;
case MediaPlaylist::MediaPlaylistType::kEvent:
header += "#EXT-X-PLAYLIST-TYPE:EVENT\n";
break;
case MediaPlaylist::MediaPlaylistType::kLive:
if (sequence_number > 0) {
base::StringAppendF(&header, "#EXT-X-MEDIA-SEQUENCE:%d\n",
sequence_number);
}
if (discontinuity_sequence_number > 0) {
base::StringAppendF(&header, "#EXT-X-DISCONTINUITY-SEQUENCE:%d\n",
discontinuity_sequence_number);
}
break;
default:
NOTREACHED() << "Unexpected MediaPlaylistType " << static_cast<int>(type);
}
// Put EXT-X-MAP at the end since the rest of the playlist is about the
// segment and key info.
if (!init_segment_name.empty()) {
header += "#EXT-X-MAP:URI=\"" + init_segment_name + "\"\n";
}
return header;
}
class SegmentInfoEntry : public HlsEntry {
public:
SegmentInfoEntry(const std::string& file_name,
double start_time,
double duration);
~SegmentInfoEntry() override;
std::string ToString() override;
double start_time() const { return start_time_; }
double duration() const { return duration_; }
private:
const std::string file_name_;
const double start_time_;
const double duration_;
DISALLOW_COPY_AND_ASSIGN(SegmentInfoEntry);
};
SegmentInfoEntry::SegmentInfoEntry(const std::string& file_name,
double start_time,
double duration)
: HlsEntry(HlsEntry::EntryType::kExtInf),
file_name_(file_name),
start_time_(start_time),
duration_(duration) {}
SegmentInfoEntry::~SegmentInfoEntry() {}
std::string SegmentInfoEntry::ToString() {
return base::StringPrintf("#EXTINF:%.3f,\n%s\n", duration_,
file_name_.c_str());
}
class EncryptionInfoEntry : public HlsEntry {
public:
EncryptionInfoEntry(MediaPlaylist::EncryptionMethod method,
const std::string& url,
const std::string& key_id,
const std::string& iv,
const std::string& key_format,
const std::string& key_format_versions);
~EncryptionInfoEntry() override;
std::string ToString() override;
private:
const MediaPlaylist::EncryptionMethod method_;
const std::string url_;
const std::string key_id_;
const std::string iv_;
const std::string key_format_;
const std::string key_format_versions_;
DISALLOW_COPY_AND_ASSIGN(EncryptionInfoEntry);
};
EncryptionInfoEntry::EncryptionInfoEntry(MediaPlaylist::EncryptionMethod method,
const std::string& url,
const std::string& key_id,
const std::string& iv,
const std::string& key_format,
const std::string& key_format_versions)
: HlsEntry(HlsEntry::EntryType::kExtKey),
method_(method),
url_(url),
key_id_(key_id),
iv_(iv),
key_format_(key_format),
key_format_versions_(key_format_versions) {}
EncryptionInfoEntry::~EncryptionInfoEntry() {}
std::string EncryptionInfoEntry::ToString() {
std::string method_attribute;
if (method_ == MediaPlaylist::EncryptionMethod::kSampleAes) {
method_attribute = "METHOD=SAMPLE-AES";
} else if (method_ == MediaPlaylist::EncryptionMethod::kAes128) {
method_attribute = "METHOD=AES-128";
} else if (method_ == MediaPlaylist::EncryptionMethod::kSampleAesCenc) {
method_attribute = "METHOD=SAMPLE-AES-CENC";
} else {
DCHECK(method_ == MediaPlaylist::EncryptionMethod::kNone);
method_attribute = "METHOD=NONE";
}
std::string ext_key = "#EXT-X-KEY:" + method_attribute + ",URI=\"" + url_ +
"\"";
if (!key_id_.empty()) {
ext_key += ",KEYID=" + key_id_;
}
if (!iv_.empty()) {
ext_key += ",IV=" + iv_;
}
if (!key_format_versions_.empty()) {
ext_key += ",KEYFORMATVERSIONS=\"" + key_format_versions_ + "\"";
}
if (key_format_.empty())
return ext_key + "\n";
return ext_key + ",KEYFORMAT=\"" + key_format_ + "\"\n";
}
double LatestSegmentStartTime(
const std::list<std::unique_ptr<HlsEntry>>& entries) {
DCHECK(!entries.empty());
for (auto iter = entries.rbegin(); iter != entries.rend(); ++iter) {
if (iter->get()->type() == HlsEntry::EntryType::kExtInf) {
const SegmentInfoEntry* segment_info =
reinterpret_cast<SegmentInfoEntry*>(iter->get());
return segment_info->start_time();
}
}
return 0.0;
}
} // namespace
HlsEntry::HlsEntry(HlsEntry::EntryType type) : type_(type) {}
HlsEntry::~HlsEntry() {}
MediaPlaylist::MediaPlaylist(MediaPlaylistType type,
double time_shift_buffer_depth,
const std::string& file_name,
const std::string& name,
const std::string& group_id)
: type_(type),
time_shift_buffer_depth_(time_shift_buffer_depth),
file_name_(file_name),
name_(name),
group_id_(group_id) {}
MediaPlaylist::~MediaPlaylist() {}
void MediaPlaylist::SetStreamTypeForTesting(
MediaPlaylistStreamType stream_type) {
stream_type_ = stream_type;
}
void MediaPlaylist::SetCodecForTesting(const std::string& codec) {
codec_ = codec;
}
bool MediaPlaylist::SetMediaInfo(const MediaInfo& media_info) {
const uint32_t time_scale = GetTimeScale(media_info);
if (time_scale == 0) {
LOG(ERROR) << "MediaInfo does not contain a valid timescale.";
return false;
}
if (media_info.has_video_info()) {
stream_type_ = MediaPlaylistStreamType::kPlayListVideo;
codec_ = media_info.video_info().codec();
} else if (media_info.has_audio_info()) {
stream_type_ = MediaPlaylistStreamType::kPlayListAudio;
codec_ = media_info.audio_info().codec();
} else {
NOTIMPLEMENTED();
return false;
}
time_scale_ = time_scale;
media_info_ = media_info;
return true;
}
void MediaPlaylist::AddSegment(const std::string& file_name,
uint64_t start_time,
uint64_t duration,
uint64_t size) {
if (time_scale_ == 0) {
LOG(WARNING) << "Timescale is not set and the duration for " << duration
<< " cannot be calculated. The output will be wrong.";
entries_.emplace_back(new SegmentInfoEntry(file_name, 0.0, 0.0));
return;
}
const double start_time_seconds =
static_cast<double>(start_time) / time_scale_;
const double segment_duration_seconds =
static_cast<double>(duration) / time_scale_;
if (segment_duration_seconds > longest_segment_duration_)
longest_segment_duration_ = segment_duration_seconds;
const int kBitsInByte = 8;
const uint64_t bitrate = kBitsInByte * size / segment_duration_seconds;
max_bitrate_ = std::max(max_bitrate_, bitrate);
entries_.emplace_back(new SegmentInfoEntry(file_name, start_time_seconds,
segment_duration_seconds));
SlideWindow();
}
// TODO(rkuroiwa): This works for single key format but won't work for multiple
// key formats (e.g. different DRM systems).
// Candidate algorithm:
// Assume entries_ is std::list (static_assert below).
// Create a map from key_format to EncryptionInfoEntry (iterator actually).
// Iterate over entries_ until it hits SegmentInfoEntry. While iterating over
// entries_ if there are multiple EncryptionInfoEntry with the same key_format,
// erase the older ones using the iterator.
// Note that when erasing std::list iterators, only the deleted iterators are
// invalidated.
void MediaPlaylist::RemoveOldestSegment() {
static_assert(std::is_same<decltype(entries_),
std::list<std::unique_ptr<HlsEntry>>>::value,
"This algorithm assumes std::list.");
if (entries_.empty())
return;
if (entries_.front()->type() == HlsEntry::EntryType::kExtInf) {
entries_.pop_front();
return;
}
// Make sure that the first EXT-X-KEY entry doesn't get popped out until the
// next EXT-X-KEY entry because the first EXT-X-KEY applies to all the
// segments following until the next one.
if (entries_.size() == 1) {
// More segments might get added, leave the entry in.
return;
}
if (entries_.size() == 2) {
auto entries_itr = entries_.begin();
++entries_itr;
if ((*entries_itr)->type() == HlsEntry::EntryType::kExtKey) {
entries_.pop_front();
} else {
entries_.erase(entries_itr);
}
return;
}
auto entries_itr = entries_.begin();
++entries_itr;
if ((*entries_itr)->type() == HlsEntry::EntryType::kExtInf) {
DCHECK((*entries_itr)->type() == HlsEntry::EntryType::kExtInf);
entries_.erase(entries_itr);
return;
}
++entries_itr;
// This assumes that there is a segment between 2 EXT-X-KEY entries.
// Which should be the case due to logic in AddEncryptionInfo().
DCHECK((*entries_itr)->type() == HlsEntry::EntryType::kExtInf);
entries_.erase(entries_itr);
entries_.pop_front();
}
void MediaPlaylist::AddEncryptionInfo(MediaPlaylist::EncryptionMethod method,
const std::string& url,
const std::string& key_id,
const std::string& iv,
const std::string& key_format,
const std::string& key_format_versions) {
entries_.emplace_back(new EncryptionInfoEntry(
method, url, key_id, iv, key_format, key_format_versions));
}
bool MediaPlaylist::WriteToFile(const std::string& file_path) {
if (!target_duration_set_) {
SetTargetDuration(ceil(GetLongestSegmentDuration()));
}
std::string header = CreatePlaylistHeader(
media_info_.init_segment_name(), target_duration_, type_,
sequence_number_, discontinuity_sequence_number_);
std::string body;
if (!entries_.empty()) {
const bool first_is_ext_key =
entries_.front()->type() == HlsEntry::EntryType::kExtKey;
bool inserted_discontinuity_tag = false;
for (const auto& entry : entries_) {
if (!first_is_ext_key && !inserted_discontinuity_tag &&
entry->type() == HlsEntry::EntryType::kExtKey) {
body.append("#EXT-X-DISCONTINUITY\n");
inserted_discontinuity_tag = true;
}
body.append(entry->ToString());
}
}
std::string content = header + body;
if (type_ == MediaPlaylistType::kVod) {
content += "#EXT-X-ENDLIST\n";
}
std::unique_ptr<media::File, media::FileCloser> file(
media::File::Open(file_path.c_str(), "w"));
if (!file) {
LOG(ERROR) << "Failed to open file " << file_path;
return false;
}
int64_t bytes_written = file->Write(content.data(), content.size());
if (bytes_written < 0) {
LOG(ERROR) << "Error while writing playlist to file.";
return false;
}
// TODO(rkuroiwa): There are at least 2 while (remaining_bytes > 0) logic in
// this library to handle partial writes by File. Dedup them and use it here
// has well.
if (static_cast<size_t>(bytes_written) < content.size()) {
LOG(ERROR) << "Failed to write the whole playlist. Wrote " << bytes_written
<< " but the playlist is " << content.size() << " bytes.";
return false;
}
return true;
}
uint64_t MediaPlaylist::Bitrate() const {
if (media_info_.has_bandwidth())
return media_info_.bandwidth();
return max_bitrate_;
}
double MediaPlaylist::GetLongestSegmentDuration() const {
return longest_segment_duration_;
}
void MediaPlaylist::SetTargetDuration(uint32_t target_duration) {
if (target_duration_set_) {
if (target_duration_ == target_duration)
return;
VLOG(1) << "Updating target duration from " << target_duration << " to "
<< target_duration_;
}
target_duration_ = target_duration;
target_duration_set_ = true;
}
// Duplicated from MpdUtils because:
// 1. MpdUtils header depends on libxml header, which is not in the deps here
// 2. GetLanguage depends on MediaInfo from packager/mpd/
// 3. Moving GetLanguage to LanguageUtils would create a a media => mpd dep.
// TODO: fix this dependency situation and factor this out to a common location
std::string MediaPlaylist::GetLanguage() const {
std::string lang;
if (media_info_.has_audio_info()) {
lang = media_info_.audio_info().language();
} else if (media_info_.has_text_info()) {
lang = media_info_.text_info().language();
}
return LanguageToShortestForm(lang);
}
bool MediaPlaylist::GetResolution(uint32_t* width, uint32_t* height) const {
DCHECK(width);
DCHECK(height);
if (media_info_.has_video_info()) {
*width = media_info_.video_info().width();
*height = media_info_.video_info().height();
return true;
}
return false;
}
void MediaPlaylist::SlideWindow() {
DCHECK(!entries_.empty());
if (time_shift_buffer_depth_ <= 0.0 || type_ != MediaPlaylistType::kLive)
return;
DCHECK_GT(time_scale_, 0u);
// The start time of the latest segment is considered the current_play_time,
// and this should guarantee that the latest segment will stay in the list.
const double current_play_time = LatestSegmentStartTime(entries_);
if (current_play_time <= time_shift_buffer_depth_)
return;
const double timeshift_limit = current_play_time - time_shift_buffer_depth_;
// Temporary list to hold the EXT-X-KEYs. For example, this allows us to
// remove <3> without removing <1> and <2> below (<1> and <2> are moved to the
// temporary list and added back later).
// #EXT-X-KEY <1>
// #EXT-X-KEY <2>
// #EXTINF <3>
// #EXTINF <4>
std::list<std::unique_ptr<HlsEntry>> ext_x_keys;
// Consecutive key entries are either fully removed or not removed at all.
// Keep track of entry types so we know if it is consecutive key entries.
HlsEntry::EntryType prev_entry_type = HlsEntry::EntryType::kExtInf;
std::list<std::unique_ptr<HlsEntry>>::iterator last = entries_.begin();
size_t num_segments_removed = 0;
for (; last != entries_.end(); ++last) {
HlsEntry::EntryType entry_type = last->get()->type();
if (entry_type == HlsEntry::EntryType::kExtKey) {
if (prev_entry_type != HlsEntry::EntryType::kExtKey) {
if (!ext_x_keys.empty()) {
// Increase discontinuity sequence every time key changes. Note that
// it is inconsistent to how we insert EXT-X-DISCONTINUITY tag
// currently as we only insert the tag for the first EXT-X-KEY.
// TODO(kqyang): Find out if it is necessary to insert the
// EXT-X-DISCONTINUITY tag when key changes.
++discontinuity_sequence_number_;
ext_x_keys.clear();
}
}
ext_x_keys.push_back(std::move(*last));
} else {
DCHECK_EQ(entry_type, HlsEntry::EntryType::kExtInf);
const SegmentInfoEntry* segment_info =
reinterpret_cast<SegmentInfoEntry*>(last->get());
const double last_segment_end_time =
segment_info->start_time() + segment_info->duration();
if (timeshift_limit < last_segment_end_time)
break;
++num_segments_removed;
}
prev_entry_type = entry_type;
}
entries_.erase(entries_.begin(), last);
// Add key entries back.
entries_.insert(entries_.begin(), std::make_move_iterator(ext_x_keys.begin()),
std::make_move_iterator(ext_x_keys.end()));
sequence_number_ += num_segments_removed;
}
} // namespace hls
} // namespace shaka
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